Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. PCOS is associated with multiple co-morbidities including obesity, insulin resistance, subfertility, impaired quality of life (QoL) and increased risk of type 2 diabetes. Obstructive sleep apnoea (OSA) is a common medical condition that is often undiagnosed, particularly in women. Obesity is a common risk factor for OSA and PCOS and OSA is associated with comorbidities similar to those observed in patients with PCOS such as insulin resistance, increased risk of type 2 diabetes, and impaired QoL. Hence it is not surprising that OSA and PCOS might co-exist.